Help with Sony DXC-M2 broadcast camera/power/transformer - UK Vintage Radio Repair and Restoration Discussion Forum

Henenen · 25th Feb 2016, 6:06 pm

To my great delight I have acquired a 1985 Sony DXC-M2 3-tube video camera.

However within 30 seconds to a minute of powering it up, the power adaptor/transformer switched off and now I can't get it to switch on again.

Tried the plug fuse, tried an alternate kettle lead. Opened up the power supply and looked for an obvious internal fuse - couldn't see one. Would they even have a fuse?

Attached are pictures of what the power unit looks like.
It powers the camera but can also has a composite signal (BNC) output. (The camera has a video output also).
It's model number is a Sony CMA-8CE.

Anything else I could try? Could it be a dry joint? (Would a joint likely crack after 30 seconds of use?)

Thanks!

Welsh Anorak · 25th Feb 2016, 7:47 pm

Hi there
Although I'm not familiar with that particular unit I would suspect it's a switch-mode power supply because of the wide voltage input range. Quite probably it's not been used for a while. It's likely to have a couple of switching transistors and some capacitors which probably have failed and tken out the transistors, just like they did on the C7 video recorder.
You'll have to open the bonnet and have a look. I'll bet there's a blackened fuse in there - don't replace it! Report back and we'll try and help. Usual question - no offence intended - how experienced are you in reapir of this type of equipment?
Glyn

AC/HL · 26th Feb 2016, 1:29 am

Those voltage ranges are quite specific, i.e. not straight 110-240, bit in two or more steps.
Check for an internal switch or link/s, and a blackened fuse.

Nicklyons2 · 26th Feb 2016, 1:45 am

Isn't the voltage selector centre a fuse holder? By the way was it set for 240V or had someone left it set to a lower voltage? Is the Cannon connector a 3 pin Audio Out or a 4 pin DC out? If it's a DC out: do you feed the camera power via the multicore OR the 4 pin?

Henenen · 1st Mar 2016, 12:02 am

Hi, the voltage was set to 240v, yes.

I unscrewed the voltage selector and there was a weird metal chamber inside that looked like it could contain a fuse, but I later found the fuse under a circuit board at the other end of the unit. Please could someone explain what that chamber was?

So, the fuse was up the other end, near the power switch. It was hard to see as the PCB holding it wouldn't lift very far out. The fuse looked OK though, no blackening or break in the wire.

How experienced am I... not very I'm afraid. Need very basic steps/suggestions.

Nicklyons2 · 1st Mar 2016, 11:00 am

As I said, the mains input fuse fits in the 'weird chamber'. Can't remember what the original value was. Try a 1.6A or 2A anti-surge type with a 3A plug fuse and see if the fuse/es go violently or, if you're lucky, it works. If you've a variac wind the voltage up on that. If it's faulty and you're 'lucky' the input filter capacitor or bridge rectifier may be all that's faulty.

kan_turk · 1st Mar 2016, 11:49 am

I would be concerned as to what became of the original fuse - could it have fallen out unnoticed? As there must have been a fuse for the unit to initially power up even if it was for only 30 secs - fuse on PCB will be on low voltage output side

Henenen · 1st Mar 2016, 12:40 pm

I was very careful when I unscrewed it last night, nothing fell out of it.

Therefore there was definately nothing in that chamber when it powered up for 30 seconds.

25th Feb 2016, 6:06 pm	#1
Henenen Tetrode Join Date: Mar 2011 Location: London, UK. Posts: 81	Help with Sony DXC-M2 broadcast camera/power/transformer To my great delight I have acquired a 1985 Sony DXC-M2 3-tube video camera. However within 30 seconds to a minute of powering it up, the power adaptor/transformer switched off and now I can't get it to switch on again. Tried the plug fuse, tried an alternate kettle lead. Opened up the power supply and looked for an obvious internal fuse - couldn't see one. Would they even have a fuse? Attached are pictures of what the power unit looks like. It powers the camera but can also has a composite signal (BNC) output. (The camera has a video output also). It's model number is a Sony CMA-8CE. Anything else I could try? Could it be a dry joint? (Would a joint likely crack after 30 seconds of use?) Thanks! Attached Thumbnails

25th Feb 2016, 7:47 pm	#2
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,927	Re: Help with Sony DXC-M2 broadcast camera/power/transformer Hi there Although I'm not familiar with that particular unit I would suspect it's a switch-mode power supply because of the wide voltage input range. Quite probably it's not been used for a while. It's likely to have a couple of switching transistors and some capacitors which probably have failed and tken out the transistors, just like they did on the C7 video recorder. You'll have to open the bonnet and have a look. I'll bet there's a blackened fuse in there - don't replace it! Report back and we'll try and help. Usual question - no offence intended - how experienced are you in reapir of this type of equipment? Glyn

26th Feb 2016, 1:29 am	#3
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Help with Sony DXC-M2 broadcast camera/power/transformer Those voltage ranges are quite specific, i.e. not straight 110-240, bit in two or more steps. Check for an internal switch or link/s, and a blackened fuse.

26th Feb 2016, 1:45 am	#4
Nicklyons2 Octode Join Date: Jan 2013 Location: Barnsley, South Yorkshire, UK. Posts: 1,517	Re: Help with Sony DXC-M2 broadcast camera/power/transformer Isn't the voltage selector centre a fuse holder? By the way was it set for 240V or had someone left it set to a lower voltage? Is the Cannon connector a 3 pin Audio Out or a 4 pin DC out? If it's a DC out: do you feed the camera power via the multicore OR the 4 pin?

1st Mar 2016, 12:02 am	#5
Henenen Tetrode Join Date: Mar 2011 Location: London, UK. Posts: 81	Re: Help with Sony DXC-M2 broadcast camera/power/transformer Hi, the voltage was set to 240v, yes. I unscrewed the voltage selector and there was a weird metal chamber inside that looked like it could contain a fuse, but I later found the fuse under a circuit board at the other end of the unit. Please could someone explain what that chamber was? So, the fuse was up the other end, near the power switch. It was hard to see as the PCB holding it wouldn't lift very far out. The fuse looked OK though, no blackening or break in the wire. How experienced am I... not very I'm afraid. Need very basic steps/suggestions. Attached Thumbnails

1st Mar 2016, 11:00 am	#6
Nicklyons2 Octode Join Date: Jan 2013 Location: Barnsley, South Yorkshire, UK. Posts: 1,517	Re: Help with Sony DXC-M2 broadcast camera/power/transformer As I said, the mains input fuse fits in the 'weird chamber'. Can't remember what the original value was. Try a 1.6A or 2A anti-surge type with a 3A plug fuse and see if the fuse/es go violently or, if you're lucky, it works. If you've a variac wind the voltage up on that. If it's faulty and you're 'lucky' the input filter capacitor or bridge rectifier may be all that's faulty.

1st Mar 2016, 11:49 am	#7
kan_turk Hexode Join Date: Mar 2014 Location: Dublin, Ireland Posts: 398	Re: Help with Sony DXC-M2 broadcast camera/power/transformer I would be concerned as to what became of the original fuse - could it have fallen out unnoticed? As there must have been a fuse for the unit to initially power up even if it was for only 30 secs - fuse on PCB will be on low voltage output side

1st Mar 2016, 12:40 pm	#8
Henenen Tetrode Join Date: Mar 2011 Location: London, UK. Posts: 81	Re: Help with Sony DXC-M2 broadcast camera/power/transformer I was very careful when I unscrewed it last night, nothing fell out of it. Therefore there was definately nothing in that chamber when it powered up for 30 seconds.